Sodas and other sugary beverages could get more expensive in San Francisco under a tax being proposed by a city supervisor.

At Tuesday's board meeting, Supervisor Scott Wiener plans to propose a 2-cents-per-ounce tax on sugary beverages that have at least 25 calories per 12 ounces.

The proposal would go on the November 2014 ballot to be decided by the city's voters. It would require two-thirds approval to pass.

The tax is estimated to generate $31 million in revenue, which would be used to fund recreation and nutrition programs in the city's schools and parks, according to Wiener's office.

The supervisor said in a statement that he decided to introduce the legislation after speaking with health researchers and advocates about the widespread problems of obesity and diabetes.

"We are experiencing an epidemic of health problems caused by sugary beverages," Wiener said. "We have a responsibility to act to confront this escalating public health challenge."

Wiener's office estimates that even a one-cent-per-ounce tax could cut consumption of the sugary drinks by up to 10 percent, and that the tax would also lead to reduced costs in treating obesity or other related ailments.

The tax would not apply to diet soda, natural juices, milk, infant formula or medical drinks.

According to Wiener's office, the idea of a sugary beverage tax has been endorsed by organizations such as the American Heart Association, the American Diabetes Association and the San Francisco Medical Society.